An Australian Spitfire pilot who was shot down 70 years ago has finally been honoured with a full military funeral in northern France.

Family members and RAAF representatives travelled to the town of Hardifort for the burial of Sergeant William Smith, who died after his Spitfire crashed near the town following an aerial duel with German fighters over the English Channel in 1942.

His remains and the wreckage of his plane were found buried deep under a wheat field last October, by a film crew who were looking for another Spitfire believed to have crashed in the area.

Sergeant Smith's brother, 84-year-old Bert Smith, watched as the airman's remains were lowered into the grave at the town's Commonwealth war cemetery, not far from the scene of the crash.